Acid catalyst with a sulfated zirconia base and its uses

ABSTRACT

The invention relates to an acid catalyst containing a substantial quantity of supported or mass sulfated zirconia and at least one hydrogenating transition metal. This catalyst is characterized by the fact that the sulfated zirconia is in crystallized form and that it shows a specific surface area greater than or equal to 135 m 2 /g, a pore volume greater than or equal to 0.16 cm 3 /g and an average pore diameter greater than or equal to 20 Angstroms (20×10 −10  m). The invention also relates to methods of making this catalyst and to the uses of this catalyst in hydrocarbon transformation chemical reactions requiring the use of an acid type catalyst, such as for example, isomerization, alkylation, oligomerization reactions or even light hydrocarbon dehydration reactions, and also heavier hydrocarbon hydrocracking and hydroisomerization reactions. In a preferred embodiment of the method of the present invention, a hydrated zirconia gel is washed with a soluble polar organic solvent (other than water). In accordance with the method including this washing step, a solid acid catalyst containing pure mass sulfated zirconia in a crystallized form has a surface area greater than or equal to 150 m 2 /g, a pore volume greater than or equal to 0.2 cm 3 /g, and more preferably greater than or equal to 0.25 cm 3 /g, and an average pore diameter greater than or equal to 20 Angstroms (20×10 −10  m) and preferably greater than or equal to 30 Angstroms (30×10 −10  m).

This is a continuation-in-part application of pending application Ser.No. 09/168,920, filed on Oct. 9, 1998 now U.S. Pat. No. 6,180,555, andclaiming priority to French application FR-9712762, filed October 13,1997, of which the disclosures are herein incorporated by reference.

This invention relates to an acid catalyst that contains a substantialamount of sulfated zirconia and at least one hydrogenating transitionmetal as well as to its uses in hydrocarbon transformation chemicalreactions requiring the use of an acid type catalyst, such as forexample those of isomerization, alkylation, oligomerization or yetdehydration reactions of light hydrocarbons, but also hydrocracking orhydroisomerization reactions of heavier hydrocarbons.

In the following, the term “sulfated zirconia” does not mean zirconiumsulfate or zirconyle stoichiometric sulfate, but zirconium (zirconiumdioxide) more or less sulfated, where the sulfate content can be lessthan that of the above-mentioned stoichiometric compounds.

BACKGROUND OF THE INVENTION

As known, the oil industry uses many methods to modify hydrocarbonstructures in order to obtain molecules whose properties are suitablefor the sought use. These procedures usually call for one or morecatalysts that have to be specifically adapted to the chemicaltransformation one wants to complete, as well as to the requirementstied to the implementation of the method.

Many of these hydrocarbon transformation chemical reactions are donewith an acid type catalyst. Such is the case, for example, of reactionstaking place in the isomerization process of paraffin, which appliesmostly to light gasolines and allows for the transformation of linearparaffin into ramified paraffin, whose octane number is higher.

In this method, the acid catalysts most used today are catalysts with analuminum chloride base supported on alumina (meaning deposited on analumina support). Indeed, these extremely active catalysts make itpossible to obtain an isomerization reaction at low temperatures, around150° C., with a thermodynamic balance that is very favorable to theformation of the sought products.

However, this type of catalyst does have a certain number ofinconveniences tied in particular to the fragile nature of its activesites. Indeed, the aluminum chloride is a very unstable compound: it isirreversibly destroyed by water, oxygen, oxygen-containing or sulfurcompounds. These products must therefore be entirely eliminated from theload being treated, which is quite costly and restricting. Furthermore,the loading of the reactors when starting the unit or, when the catalysthas been replaced, must be done in perfectly anhydrous conditions,without any trace of water or oxygen. Moreover, the preservation of theactive sites during the operation requires a constant injection ofdopants such as hydrochloric acid or other chlorine products; the excessacid must then be removed when leaving the reactor and invariablycreates a corrosion problem. Lastly, despite all these precautions, thecatalyst is progressively destroyed and must be replaced periodicallysince it is not regenerable.

This is why the research relating to acid catalysts has looked to thecreation of new compounds with catalytic properties similar to those ofthe aluminum chloride but without having the same inconveniences as thelatter. This is specifically the case of the sulfated zirconia.

Thus, U.S. Pat. No. 3,032,599 (Phillips Petroleum) is one of the firstpatents to describe the application of sulfated zirconia toisomerization and alkylation of hydrocarbons: the proposed catalysts aremade entirely of zirconia gel, possibly containing small quantities of ametallic promoter. They are prepared by the precipitation of a zirconylesalt in solution in water, by an addition to the base. The zirconia gelobtained is then sulfated and then activated at approximately 500° C.These catalysts do indeed show acid catalytic properties but, however,they are not very satisfactory. Indeed, they have a low surface area,which can explain their relatively mediocre performance as far asisomerization reactions are concerned. Furthermore, these powderycatalysts are for the most part unusable as such in an industrialreactor.

Also, U.S. Pat. No. 3,132,110 (Union Oil) describes the properties of aseries of acid catalysts with a base of hydrated zirconia containingsulfate radicals, pure or preferably combined with alumina. Thepreparation methods of these catalysts rest mostly on the decompositionof a zirconia sulfate salt in solution in water, by the hydrolysis in abasic medium or by thermal decomposition. The catalysts obtained in thismanner are indeed active in a good number of reactions requiring the useof an acid catalyst, and have the advantage of being perfectlyregenerable. Nevertheless, their activity has proved to be relativelylimited and these catalysts must be used at high temperatures, forexample over 370° C. in the case of the isomerization reaction ofparaffin. Well, at such temperatures, not only is this reactiondisadvantaged thermodynamically but, in addition, the catalyst'sdeactivation speed is accelerated by depositing coke on its surface.

Along the same lines of replacing aluminum chloride based catalysts inisomerization with more stable catalytic compounds, U.S. Pat. No.4,406,821 (Exxon) proposes a catalyst consisting of a sulfated oxidedeposited on an alumina support. This oxide is preferably a tungsten orhafnium oxide, but can also be a niobium, thallium, zirconium oxide, ora mixture thereof. This catalyst is prepared by impregnation of thealumina support with a solution of a salt of the chosen metal, followedby a calcination at a high temperature, then a sulfation using asulfuric acid water solution. The catalyst obtained by this method doespossess the acid properties and it performs particularly well in theetherification reactions of phenols. Nevertheless, these catalysts arenot well adapted to the isomerization reaction of paraffin at lowtemperatures, where their activity seems to be limited.

In general, the acid catalysts proposed in the prior art and which couldreplace the alumina chloride based isomerization catalysts are thereforequite unsatisfactory due to their lack of activity.

Continuing her research in the field of sulfated zirconia basedcatalysts, the petitioner has issued the hypothesis that the lack ofactivity of the formulas proposed to date was tied to the actualstructure of these catalysts that do not present enough accessibleactive sites to the reactive molecules. She has deduced that this wasdue to a maladjusted porosity and to a catalyst surface area too smallin the prior art's catalysts, and an incapacity to control theseparameters.

This is why the petitioner has focused her efforts on the problem, atthe time unsolved, of improving the exchanges between the activecatalyst sites and the molecules to be converted. She assumed it wasnecessary to succeed in modifying the structure of these sulfatedzirconia based catalysts, and she then focused on creating catalyststhat have a more adequate porosity and surface area, appropriate forgiving them a better activity compared to what has been accomplished todate. In doing so, she has also discovered a certain number of originalmethods for controlling the porosity of these catalysts and shaping themso as to obtain the desired active structures.

SUMMARY OF THE INVENTION

So, the applicant has perfected a solid acid catalyst, containing asubstantial quantity of supported or mass sulfated zirconia and at leastone hydrogenating transition metal. This catalyst is different in thatthe said sulfated zirconia is in a crystallized form and shows a surfacearea greater than or equal to 135 m²/g, preferably greater than or equalto 150 m²/g, a pore volume greater than or equal to 0.16 cm³/g,preferably greater than or equal to 0.2 cm³/g, and more preferablygreater than or equal to 0.25 cm³/g and an average pore diameter greaterthan or equal to 20 Angstroms (20×10⁻¹⁰ m).

Here and in the following, the characteristics of the surface area, thepore volume and the average pore diameter are mentioned in reference tothe method of determination called B.E.T. (Brunauer, Emmett, Teller) byadsorption of nitrogen, well known to any person skilled in the art, asdescribed in the work by S. Lowell and J. E. Shields, “Powder surfaceArea and Porosity”, Powder Technology Series (1984). The surface area Sis deducted from the B.E.T. linear transformation at five points, thepore volume Vp is determined according to the quantity of nitrogenabsorbed in a relative pressure P/Po=0.985 and the average pore diameterRp is calculated following the formula Rp 2Vp/S.

In the catalyst consistent with the present invention, the zirconia(zirconium dioxide) is partially or totally sulfated. Favorably, thesulfate content is less than the stoichiometric quantities: preferably,the sulfur content in form of sulfate is between 1% and 10% by weightcompared to the weight of the zirconia, and even more preferably,between 1% and 5% by weight.

According to the invention, the structure and texture characteristicsthat define the catalyst have been optimized by acting on themanufacturing method of these catalysts: by resorting to adequatemethods such as the deposit of sulfated zirconia on an appropriatesupport or the potential use of a structuring agent, by acting both onthe nature and the sequence of the manufacturing stages of thesecatalysts, by implementing appropriate thermal treatments (inparticular, calcinations), it has been possible to modify the structureand the texture of sulfated zirconia based catalysts in order to selectthe most active formulas.

In a preferred embodiment of the method of the present invention, ahydrated zirconia gel is washed with a soluble polar organic solvent(other than water). In accordance with the method including this washingstep, a solid acid catalyst containing pure mass sulfated zirconia in acrystallized form has a surface area greater than or equal to 150 m²/g,a pore volume greater than or equal to 0.2 cm³/g, and more preferablygreater than or equal to 0.25 cm³/g, and an average pore diametergreater than or equal to 20 Angstroms (20×10⁻¹⁰ m) and preferablygreater than or equal to 30 Angstroms (30×10⁻¹⁰ m).

When compared to the sulfated zirconia based catalysts known to date,the catalyst according to the invention shows a crystalline structurethat helps give it a more open porosity, and a higher specific surfacearea. This generates a better ease of access for the reactants to activesites that are themselves more numerous, which, in turn, gives thecatalyst an increased activity: for the isomerization reaction of linearparaffin, it has been proved to possess an activity close to that oftraditional alumina chloride based catalysts. As the latter, theinvention's catalyst stays active at low temperatures (approximately150° C.), thus in conditions for which the isomerization reaction oflinear paraffins is thermodynamically favorable to the sought ramifiedproducts.

Furthermore, even though the invention's catalyst has catalyticproperties similar to those of traditional aluminum chloride catalysts,it does not have the same disadvantages: much more stable, it has indeedproved to be less sensitive to the inevitable presence of smallquantities of water and sulfur compounds in the loads to be converted.Indeed, the water does not act on the catalyst's active sites in adestructive manner but in an inhibitory manner, and thus in a reversiblemanner, since this catalyst can easily be regenerated. In the samemanner, there is no need for any specific precautions to be taken whenstoring and loading this catalyst.

Also, the invention's catalyst has the undeniable advantage of beingperfectly regenerable, by the combustion of coke deposits created duringthe isomerization reaction. This property is particularly interestingfrom an economic point of view considering the high cost of catalysts.The regeneration can be handled advantageously on site, meaning withouthaving to remove the catalyst from the reactor, which avoids themultiplication of unloading and loading functions of the latter.

It is then possible to consider a continuous catalyst regenerationmethod, where the catalyst circulates between a reactor in which theconversion takes place and a catalyst regeneration chamber. Such amethod avoids having to periodically stop the unit in order toregenerate the catalyst and more importantly to have, in the reactor, acatalyst permanently kept at the height of its activity.

Furthermore, the use of the invention's catalyst does not require theinjection of corrosive dopants in the reactor. As a result, thecorrosion is reduced within the unit which in turn allows for a longerlife time of the unit. It also results in an enhancement of the securitytied to the method, and in particular to a reduction of pollution andaccident risks connected with the use of such dopants, especially thetoxic dopants.

Lastly, the invention's catalyst has proved to be remarkably active in acertain number of reactions other than the isomerization of lightparaffin. Among others, the alkylation reactions, the dehydrationreactions, and mostly the hydrocracking and hydroisomerization reactionsof longer light paraffins (consisting of more than 7 carbon atoms).

DETAILED DESCRIPTION OF THE INVENTION

Concurrently, the petitioner have perfected several original methodsallowing for the control of both the structure and the texture of thesulfated zirconia based catalysts, and therefore for the preparation ofa catalyst with a controlled porosity as described previously. Thus theinvention also relates to these preparation procedures, which will beexplained in more detail in the description and the examples hereafter.

In order for the catalyst to be sufficiently active, the sulfatedzirconia that it contains must be in a crystallized form, meaning itmust not be in an amorphous form. The preferred crystallized structuresare the quadratic and monoclinic type structures. The determination ofthe crystalline structure of the zirconia is created, in a well-knownmanner, by x-ray diffraction.

The presence of a hydrogenating transition metal is necessary for thestability of the catalytic activity of the invention's catalyst. Thishydrogenating transition metal is preferably an element pertaining togroup VIII of the Periodic table of elements, and in particular anelement of the group consisting of platinum, ruthenium, rhodium,palladium, osmium and iridium, where the platinum is most preferred. Thecrystalline structure of the zirconia is not affected in a sensitivemanner by the presence of this hydrogenating transition metal.

The acid catalyst, according to the invention, is of the solid type. Itcan exist under all forms to which the trade person usually resorts forthe implementation of solid catalysts, and in particular in the form ofparticles such as beads, extrusions, and pellets. It has a visiblefilling density preferably between 0.5 and 3.

Preferably, its surface area is greater than or equal to 150 m²/g, itspore volume is greater than or equal to 0.25 cm³/g and its average porediameter is greater than or equal to 30 Angstroms (30×10⁻¹⁰ m).

The crystallized sulfated zirconia present in the invention's catalystcan have two distinct forms: one called “supported” or another called“mass”.

In the case of a crystallized sulfated based zirconia in the “supported”form, the sulfated zirconia crystals are deposited on a support that hasalready formed. The latter can be any kind of support usually used forindustrial catalysts, such as alumina, silica, silica-alumina, silicate,alumino-silicate, magnesia, zeolite, active carbon, gallium, titanium,thorium, or boron oxide, clay and any combination of these supports.Preferably, the invention's catalyst then contains between 50% and 95%by weight of classic support, on which 5% to 50% of sulfated zirconia byweight is deposited.

In the case of a crystallized sulfated zirconia based catalyst in “mass”form, such catalyst contains zirconia crystals in its matrix, alone ormixed with a structuring agent, which allows for a better control of thecatalyst's structure and texture. This structuring agent can be anyrefractory mineral oxide usually used in the industry, and can inparticular be chosen from the group consisting of aluminas, silicas,silica-aluminas, alumino-silicates, clays and combinations of thesecompounds. The catalyst can then contain from 0.5 to 100 percent byweight of the sulfated zirconia and preferably from 20 to 80 percent byweight.

In the case of the crystallized sulfated zirconia based catalyst in“pure mass” form, such catalyst contains zirconia crystals in itsmatrix, alone or mixed with a binder material, whose only function is tofacilitate the shaping of the catalyst, considering the powderycharacteristic of the zirconia. This binder material can be anyrefractory mineral oxide usually used in the industry for that purpose,and can in particular be chosen from the group consisting of aluminas,silicas, silica-aluminas, alumino-silicates, clays and combinations ofthese compounds. The catalyst can then contain from 5 to 50 percent byweight and preferably from 10 to 30 percent by weight of the bindermaterial.

The invention's acid catalyst can be prepared according to a certainnumber of methods detailed hereafter. These methods make it possible tohave a strong control of the textural and structural properties of thecatalyst, which is indispensable in preparing a catalyst that satisfiesthe characteristics of the invention, thus a highly active and usablecatalyst as is in an industrial reactor.

a) Supported Sulfated Zirconia Based Catalyst

The solid acid catalyst, with a sulfated zirconia base, deposited on acatalytic support can be prepared according to a method consisting ofthe following steps:

deposit of hydrated zirconia on the catalytic support

calcination of the solid

sulfation of the solid

deposit of a hydrogenating transition metal

final calcination of the solid.

The deposit of the hydrated zirconia on the catalytic support can bedone by impregnation of the mentioned support through a solution ofzirconium salt followed by drying the solid obtained.

The deposit of a hydrogenating transition metal on the catalytic supportcan be done before the deposit of zirconia or at any other time duringthe preparation but must be done prior to the final calcination.

b) Mass Sulfated Zirconia Based Catalyst

In these catalysts, the matrix has a base of zirconia, pure or mixedwith a structuring agent containing a refractory mineral oxide base or amixture of refractory mineral oxides.

The solid acid catalyst, with a mass sulfated zirconia base mixed with astructuring refractory mineral oxide, can be prepared according to amethod consisting of the following steps:

addition of a basic solution to a solution of zirconium salt, so as toproduce a precipitation of hydrated zirconia,

addition of salt precursor solution to the structuring refractorymineral oxide

addition of a basic solution, so as to produce a precipitation of thestructuring refractory mineral oxide

washing then drying of the product obtained

shaping of the solid

sulfation of the solid

deposit of the hydrogenating transition metal

final calcination

The precipitation of the zirconia can be done before or after that ofthe structuring agent. The steps consisting of the deposit of thehydrogenating transition metal and the shaping can be done before orafter the sulfation but must be done prior to the final calcination.

According to a first alternative, the solid acid catalyst, with a masssulfated zirconia base mixed with a structuring refractory mineraloxide, can be prepared according to another method consisting of thefollowing steps:

addition of a basic solution to a solution of zirconium salt and of asalt precursor to the structuring refractory mineral oxide, so as toproduce a co-precipitation of zirconia and of the structuring refractorymineral oxide.

washing, drying of the precipitate obtained

shaping of the solid

sulfation of the solid

deposit of the hydrogenating transition metal

final calcination

The steps consisting of the deposit of the hydrogenating transitionmetal and the shaping can be done before or after the sulfation but mustbe done prior to the final calcination.

The solid acid catalyst, with a pure mass sulfated zirconia base can beprepared according to a method consisting of the following steps:

addition of a basic solution to a solution of zirconium salt, so as toproduce a precipitation of hydrated zirconia

washing then drying of the precipitate obtained

sulfation of the solid

shaping of the solid

deposit of the hydrogenating transition metal

final calcination

The steps consisting of the deposit of the hydrogenating transitionmetal and shaping can be done before or after the sulfation, but must bedone prior to the final calcination.

The solid acid catalyst according to the present invention, with acrystallized “pure mass” sulfated zirconia base, can be preparedaccording to one embodiment of the invention by a method comprising thesteps of:

a) adding a basic solution to a zirconium salt solution to produce amixture containing a precipitate of hydrated zirconia,

b) filtering the mixture and washing the precipitate with water to forma solid,

c) washing the solid with a water soluble polar organic solvent, atleast one time,

d) drying the solid,

e) sulfating the solid,

f) shaping the solid and first calcining at a temperature of at least550° C.,

g) depositing the hydrogenating transition metal, and

h) final calcining.

The steps consisting of the deposit of the hydrogenating transitionmetal and shaping can be done before or after the sulfation, but must bedone prior to the final calcination. The solid is dried only after thestep of washing with a water soluble polar organic solvent. Preferably,the solubility in water of this solvent is of at least 5 g/100 ml. Inother words, at least 5 g of solvent may be dissolved in 100 ml of waterat 23° C., under atmospheric pressure (760 mm Hg). More preferably, thesolvent and water are miscible in all proportions. The boiling point ofthe solvent is preferably less than the one of water (i.e. less than100° C.). During the washing step, the gel is washed at least once andpreferably several times (at least three times). After drying thezirconia gel treated in this way and sulfating the same, the resultingproduct may be crystallized by subjecting it to a calcination and,surprisingly, still keep high textural properties, in particular aspecific surface area or 150 m²/g or more, a pore volume of at least 0.2cm³/g and an average pore radius of at least 20 Å.

It should be noted that, when shaping this type of catalyst, usually abinder material is preferably incorporated. This binder material makesit easier to shape the catalyst into extrudates or other pellets, to beused in an industrial reactor. This binder is not a structuring agent.The catalyst comprises between 5 to 50 wt % of this binder andpreferably 10 to 30 wt %. The binder may be selected from the groupconsisting of aluminas, silicas, silica-aluminas, alumino-silicates,clays and combinations thereof.

No matter what type of catalyst is being prepared or what method ofpreparation is being used therefore:

the zirconium salt to be used in the process of the invention can beselected from the group consisting of nitrates, chlorides, acetates,formates, oxalates of zirconium and zirconyles as well as zirconiumpropylates and butylates

the salts that can be used as precursors of the structuring refractorymineral oxide, if necessary, are well known to the person skilled in theart. If for example, the aforementioned mineral oxide is an alumina, wewill use an aluminum salt that can favorably be selected from the groupconsisting of nitrates, chlorides and aluminum sulfates.

the basic solution used can be any-solution that will help achieve theprecipitation of a hydrated oxide from a solution of salt precursor ofsaid oxide by increasing the pH. For example, it can be that of anammonia solution or any other base known to the person skilled in theart.

the step consisting of the sulfation of the catalyst is done byimpregnating the solid with a sulfating agent, then drying. Thesulfating agent can be liquid, gaseous or in solution; for example thefollowing can be used, a sulfuric acid pure or in solution, an aqueoussolution of ammonium sulfate, or any other precursor of sulfate ions. Toachieve this sulfation, any impregnation technique known to the personskilled in the art can be used. This step usually ends by a calcinationof the sulfated solid.

the step consisting of the shaping of the invention's solid catalyst,necessary when it contains mass zirconia, makes it possible to clump thecatalyst powder in the form of particles (for example beads, extrusionsor pellets) in order to be able to directly use this catalyst in anindustrial reactor. To facilitate this operation, it may be necessary toadd a binding material (alumina xerogel or any other industrial bindingmaterial) to the catalyst powder, then to knead the mixture obtainedbefore proceeding with the actual shaping by extrusion, “oil drop”,container method, or any other method known for the shaping ofindustrial catalysts. This step ends with a calcination.

the step consisting of the deposit of the hydrogenating transition metalis achieved by impregnation of the solid with a solution ofhydrogenating transition metal compound, followed by a drying step; whenthis metal is platinum, the impregnation step is carried out with asolution of a platinum compound that can be selected from the groupconsisting of chloroplatinic acid and complex platinum compounds.

the first calcination, usually completed after the shaping, must takeplace at a temperature that is sufficiently high, that is to say greaterthan or equal to 550° C. This is necessary in order to obtain a zirconiawith an adequate crystalline structure.

The preparation methods described above are only suggestions for thepreparation of a catalyst that is consistent with the invention. Ofcourse, they have no restricted character. If necessary, the personskilled in the art will know exactly how to adapt them throughadditional well-known operations such as, for example, the ripening ofgels, washing with solvents, drying and calcination.

The invention's acid catalyst can be used in any hydrocarbontransformation chemical reaction requiring the use of an acid, or superacid, catalyst.

This catalyst has proved to be especially advantageous for isomerizationreactions of linear paraffin into ramified paraffin at a temperaturebelow 200° C., but it can just as well be used in the isomerization ofolefins and the isomerization of cyclical and aromatic compounds. It canalso be used in an alkylation reaction, an oligomerization reaction or ahydrocarbon dehydration reaction.

Furthermore it can be used, quite advantageously, in a treatment methodof a hydrocarbonic section containing a substantial quantity of longchain paraffin, whether linear or slightly ramified, such as for exampleparaffin stemming from a Fischer-Tropsch type synthesis (hydrocarbonsynthesis from the CO+H₂ mixture). The transformation by hydrocrackingor by hydroisomerization of this paraffin is often necessary in order toobtain either “large” products (medium gasolines, naphtas, ordistillates) or specialties (high quality paraffin or lubricants). Theoperating conditions must then be adjusted in relation to the reactionthat is favored (hydrocracking or hydroisomerization) and to the desiredlevel of conversion. Preferably they will be as follows: a temperaturebetween 20° C. and 200° C. (preferably between 50° C. and 150° C.), apressure between 5×10⁵ and 100×10⁵ Pa (preferably between 20×10⁵ and60×10⁵ Pa), a molecular hydrogen/hydrocarbon H₂/HC ratio to be convertedbetween 1 and 20 (preferably between 5 and 15).

The invention's catalyst can be stored or loaded in a reactor withouttaking any specific precautions. It is however preferable to submit itto a calcination at high temperature in a dry atmosphere before usingit.

After being used, it can be regenerated by simply passing it through anoxidizing atmosphere at a temperature in the range of 400 to 700° C.

The following examples are meant to illustrate the invention. They haveno restrictive character.

EXAMPLES Preparation of Catalyst Samples Consistent with the Invention

Catalyst A

This example shows the preparation of an acid catalyst A consistent withthe invention, with a supported sulfated zirconia base.

The catalyst sample is prepared from 25 g of an alumina support,marketed by AKZO under the name CK 300, previously calcined at 600° C.

The zirconium deposit is done in a ball by impregnating the support witha solution formed by the dissolution of 3.48 g of zirconyle chloride(ZrOCl₂, 8 H₂O, marketed by Prolabo) and 0.46 g of NH₄Cl in 11 cm³ ofdistilled water, with a volume corresponding to the porous volume of thesupport.

The solid obtained is first dried overnight at 120° C. then calcined for2 hours at 600° C.

This operation is repeated twice (deposit of zirconium three times),then the solid obtained is calcined for 4 hours at 750° C.

Thereafter, the sulfation of the zirconium deposited on the surface ofthe alumina support takes place by circulating 162 cm³ of a sulfuricacid solution 5 N at room temperature for 1 hour.

Then we spin-dry the solid and dry it overnight at 120° C. and thencalcine it for 2 hours at 500° C. in a flow of dry air at 60 l. h⁻¹.

Lastly, the deposit of 0.5 percent by weight of platinum takes place: 15cm³ of a chloroplatinic acid solution at 10 g.l⁻¹ is mixed with 85 cm³of distilled water; this solution is mixed with the solid preparedpreviously, then the water is evaporated.

The solid obtained is dried overnight at 120° C. and calcined for 4hours in a flow of dry air 45 l.h⁻¹ at 500° C.

Catalyst B

This example shows the preparation of an acid catalyst B consistent withthe invention, with a mass sulfated zirconia base, mixed with astructuring refractory mineral oxide, in this case alumina.

A Zr solution is prepared by dissolving 23.93 g of ZrO(NO₃)₂, 6H₂O in239 ml of distilled water with vigorous agitation.

The hydrated zirconia gel is precipitated with vigorous agitation byadding 11 ml of an ammonia solution at 28%, still with agitation. Thefinal pH is 8.

An aluminum solution is prepared by dissolving 16.55 g of Al(NO₃)₃, 9H₂O in 50 ml of water.

This solution is poured over the zirconia gel with vigorous agitation,then 8.5 ml of ammonia at 28% is added.

After the filtration and washing until a pH 7 (redispersal in 300 ml ofwater), the gel is dried overnight at 120° C.

The shaping takes place after the grinding and kneading with 3.17 g ofalumina marketed by CONDEA under the name Pural SB (or 20% of xerogel)and 9 ml of distilled water in an extruding syringe (2 mm diameter).

After drying overnight at 120° C., the extruded materials are calcinedfor 4 hours at 750° C.

The sulfation of 13.17 g of the solid is done by adding 81 ml ofsulfuric acid 5 N, for 1 hour by circulation. The spinning then takesplace over a Buchner funnel, followed by the rinsing and dryingovernight at 120° C. It ends with calcination for 2 hours at 500° C.

The quantity of recuperated material is 14.5 g.

Finally, the deposit of the platinum takes place in 10.74 g of the solidby impregnating using a rotovapor with a solution consisting of a mix of5.37 ml of a chloroplatinic acid solution at 10 g/l of Pt and 40 ml ofwater.

Lastly, the solid is dried overnight at 120° C. and then calcined for 4hours at 480° C.

Catalyst C

This example shows an alternative for the preparation of an acidcatalyst C consistent with the invention, with a mass sulfated zirconiabase mixed with a structuring refractory mineral oxide, in this casealumina.

A gel is prepared by dispersing 20 g of alumina Pural SB in 240 ml ofwater with vigorous agitation.

Then a Zr solution is prepared by dissolving 34.55 g of ZrO(NO₃)₂, 6 H₂Oin 350 ml of distilled water under agitation.

The last solution is added over the gel with vigorous agitation andproduces the precipitation of the hydrated zirconia by adding 16.25 mlof an ammonia solution at 28%, still with agitation. The final pH is8.5.

After a slow filtration and wash until it reaches pH7 (redispersal in400 ml of water), the gel is dried overnight at 120° C.

The shaping is done after the grinding and kneading of 16.1 g of thesolid with 4.03 g of Pural SB type alumina (or 20% of xerogel) and 11.5ml of distilled water in an extruding syringe (2 mm diameter).

After drying overnight at 120° C., the extruded materials are calcinedfor 4 hours at 750° C.

The sulfation of 14.25 g of the solid is done by adding 81 ml of asulfuric acid 5 N by circulation during 1 hour. The spinning then takesplace over a Buchner funnel, then the rinsing and the drying overnightat 120° C. It ends with the calcination for 2 hours at 500° C.

Finally, the deposit of platinum takes place by impregnating 14.5 g ofthis solid using a rotovapor with a solution consisting of the mixtureof 7.25 ml of a chloroplatinic acid solution at 10 g/l of Pt and 30 mlof water.

Lastly, the solid is dried overnight at 120° C. and then calcined for 4hours at 480° C.

Catalyst D

This example shows another alternative for the preparation of an acidcatalyst D consistent with the invention, with a mass sulfated zirconiabase mixed with a structuring refractory mineral oxide, in this casealumina.

21.11 g of ZrO(NO₃)₂, 6 H₂O and 27.58 g of Al(NO₃)₃, 9H₂O are dissolvedin 400 ml of distilled water with agitation (in other words 75% of ZrO₂and 25% of Al₂O₃ for 15 g of catalyst).

The hydroxide cogel is precipitated by adding 28.2 ml of an ammoniasolution at 28%, still with agitation. The final pH is 9.

After filtration and washing until a pH of 7 (redispersal in 400 ml ofwater), the gel is dried overnight at 120° C.

The shaping is done after the grinding of the whole solid and mixingwith 3.33 g of Pural SB type alumina (in other words 20% of xerogel) and8.75 ml of distilled water in an extruding syringe (2 mm diameter).

After drying overnight at 120° C. the extruded materials are calcinedfor 4 hours at 750° C.

The sulfation of 11.33 g of the solid is done by adding 75 ml of asulfuric acid 5 N by circulation for 1 hour. The spinning then takesplace over a Buchner funnel, then the rinsing and drying take placeovernight at 120° C. It ends with a calcination for 2 hours at 500° C.

Finally the deposit of platinum is done by impregnating 11.22 g of thissolid using a rotovapor with a solution consisting of a mixture of 4.6ml of a chloroplatinic acid solution at 10 g/l of Pt and 40 ml ofdistilled water.

Lastly, the solid is dried overnight at 120° C. and then calcined for 4hours at 480° C.

Catalyst E

This example shows the preparation of an acid catalyst consistent withthe invention, with a pure mass sulfated zirconia base.

35 g of ZrO(NO₃)₂, 6H₂O is dissolved in 350 ml of distilled water withagitation.

The zirconium hydroxide gel is precipitated by adding 17 ml of anammonia solution at 28%, still with agitation. The final pH is 8.5.

After filtering and washing until a pH 7 (redispersal in 350 ml ofwater), the gel is dried overnight at 120° C.

The result is 13.77 g of solid.

The sulfation is done by adding 85 ml of sulfuric acid 1 N, by staticcontact for 15 minutes. The spinning then takes place over a Buchnerfunnel, then the drying is done overnight at 120° C.

The shaping is done after the grinding of the whole solid and the mixingwith 3.4 g of Pural SB type alumina and 6.9 ml of distilled water in anextruding syringe (2 mm diameter).

After drying again overnight at 120° C., the extruded materials arecalcined for 2 hours at 625° C.

The quantity of recuperated material is 12.5 g.

Finally, the deposit of platinum takes place by impregnating in static12.3 g of this solid with a solution consisting of the mixture of 0.248g of a chloroplatinic acid at 25% of Pt and 3.8 ml of distilled water(impregnation at porous volume).

Lastly, the solid is dried overnight at 120° C. and then calcined for 4hours at 480° C.

Properties and Activity of the Catalyst Sample:

Table 1 hereafter shows the properties of the catalyst samples obtainedaccording to the methods of preparation described above.

In these five samples, the sulfated zirconia shows a quadratic typecrystalline structure. This structure has been determined by x-raydiffraction.

In the following Table, S, Vp and Rp respectively designate the surfacearea, the pore volume and the average pore diameter of the catalyst.These characteristics have been determined using the B.E.T. method(Brunauer, Emmett, Teller), by adsorption of nitrogen, as described inthe work by S. Lowell and J. E. Shields, “Powder Surface Area andPorosity”, Powder Technology Series (1984). The specific surface area Sis deducted form the BET linear transformation at five points (at therelative pressures P/Po=0.045; 0.08; 0.15; 0.25 and 0.33), the porevolume Vp is determined according to the quantity of nitrogen adsorbedat P/Po=0.985 and the average pore diameter Rp is calculated using theformula Rp=2Vp/S.

Before determining these characteristics, the sample was subjected to apretreatment by primary vacuum dearation at 250° C. for at least 8hours.

TABLE 1 ZrO₂ Al₂O₃ Sulfur (% by (% by S Vp Rp Content Catalyst weight)weight) (m²/g) (cm³/g) (10⁻¹⁰m) (%) A 17.6 82.4 151 0.34 55 2.8 B 71 29158.1 0.32 41 3.4 C 50 50 151.4 0.37 49 3.6 D 62.5 37.5 152.5 0.25 333.6 E 80 20 140 0.16 23 1.9

Note: Catalyst E has a pure mass sulfated zirconia base, the 20% ofalumina corresponds to the bond added during the shaping stage of thesolid catalyst.

The results given above show that the preparation methods perfected bythe applicant make it possible to create catalysts with a sulfatedzirconia base that have surface areas especially high, greater than whathas been done to date in the prior art. Thanks to such methods, it isnow possible to control the porosity of these catalysts and to modify itin order to obtain the desired activity.

The activity of these samples was first determined in the isomerizationreaction of the normal hexane, in conditions that are usually used forchlorine catalysts (T=145° C., P=30.1O⁵Pa, hydrogen/hydrocarbon H₂HCratio=3). Table II hereafter gives the results obtained. The activity ofthe samples is represented by the percentage by weight of 2.2 dimethylbutane (2.2 DMB) in the isomerization effluent of the normal hexane.Various spatial speeds (or ppH, load weight per unit of catalyst weightand per hour) were used:

ppH·2 or 4 kg of load.kg⁻¹ of catalyst .h⁻¹.

TABLE II isomerization of the normal-hexane Activity (% 2.2 = DMB)Catalyst ppH = 2 ppH = 4 A 29.9 21.2 B 31.4 27.9 C 31.9 28.2 D 29.6 22.1E 30.7 26.4

Thus, the catalysts consistent with the invention show excellentactivity for the isomerization of light paraffin at low temperature.This activity is close to that of the traditional catalysts with achloride alumina base.

Furthermore, the additional properties brought by the invention'scatalysts, in relation to the catalysts in the prior art, are quiteconsiderable (increased stability, ease of handling, regenerability,etc.) All this makes their use particularly advantageous in reactionsinvolving an acid, or superacid, catalyst.

Note that the activity of catalysts, consistent with the invention arealso quite remarkable in other reactions, in particular thehydroconversion of heavier, linear or slightly ramified paraffins.

Thus, catalyst E has been tested for the hydroconversion of thenormal-hexane on the one hand and the normal-hexadecane on the otherhand.

For each catalytic test, 7 g of catalyst were loaded in a reactor inanhydrous conditions (in argon atmosphere). Different operationalconditions were used where T represents the temperature, P the pressure,H₂/HC the hydrogen/hydrocarbon molecular ratio, pph the weight of theload per weight unit of the catalyst and per hour.

The results obtained are given in Tables III and IV hereafter.

TABLE III hydroconversion of the n-dodecane (n-C12) PerformancePerformance Selectivity Selectivity T P PPH Conversion i-C12 C5-C11i-C12 C5-C11 (° C.) (10⁵ Pa) H₂/HC h⁻¹ (%) (%) (%) (%) (%) 150 50 6 0.84100 0 44.2 0 44.2 125 50 12 1.25 60 8 40.1 13.3 67.9 125 50 12 1.25 91.22.2 61 2.4 66.9 115 50 6 0.84 69.6 6.3 46.6 9.2 67 115 50 12 1.25 51.66.7 35.4 13 68.6 115 50 6 0.84 70.4 0.7 26.2 1 37.2

TABLE IV hydroconversion of the n-hexadecane (n-C16) SelectivitySelectivity Selectivity T P PPH Conversion i-C16 C5-C11 C12-C15 (° C.)(10⁵ Pa) H₂/HC h⁻¹ (%) (%) (%) (%) 115 50 3 1 100 0 71.7 0.3 115 50 3 257.4 8.3 59.5 6.6 115 50 6 2 53.2 9.1 54.1 7.1 115 50 6 1 78.6 5.7 73.43.7 115 50 1.22 1 100 0 85.6 0.7 125 50 6 2 56 6.5 72.3 5.4 125 50 3 269.8 6.1 71.7 3.64

As shown in the above tables, the conversion is important starting at115° C., which shows the high activity of the catalyst at lowtemperatures.

Two reactions really take place:

hydroisomerization of the normal-dodecane into iso-dodecane(n-C12·i-C12), or of the normal hexadecane into iso-hexadecane(n-C16·i-C16);

hydrocracking of the normal-dodecane or the nomial-hexadecane intolighter hydrocarbons, with each time an excellent selectivity in favorof the intermediary hydrocarbons containing 5 to 11 carbon atoms (morethat 85% in certain conditions); they are mostly ramified pentanes andhexanes (C5 and C6) which are sought products as they are amenable tobenefication in gases due to their high octane number; thus, the C5-C6fraction produced by the hydroconversion of the normal-hexadecane at115° C., 50.10⁵ Pa, H₂/HC=6 and pph=1 (Table IV, line 4, in bold)presents a researched octane number, or RON, equal to 88.

Preparation of Additional “Pure Mass” Catalysts Consistent with theInvention

Catalyst F

This Example shows the preparation of an acid catalyst (Catalyst F) witha pure mass sulfated zirconia base, wherein the zirconia gel is washedwith acetone.

35 g of ZrO(NO₃)², 6H₂O is dissolved in 350 ml of distilled water withagitation.

The zirconium hydroxide gel is precipitated by adding 24.5 ml of anammonia solution at 28%, still with agitation. The final pH is 9.35.

The mixture is then filtered over a Buchner funnel and washed with wateruntil pH 7. After spinning on a Buchner funnel, the gel is washed withacetone, and, to this end, it is transferred into a beaker and dispersedin 350 ml of acetone. The mixture is agitated during 15 minutes, and thegel is then filtered over a Buchner funnel. After washing a second timewith acetone in the same conditions, the gel is dried overnight at 120°C.

13.85 g of solid is recovered.

The sulfatation step is carried out by adding 85 ml of sulfuric acid 1 Nto 13.65 g of the solid and by contacting them in static during 15minutes. After spinning over a Buchner funnel, a drying step isconducted overnight at 120° C.

The shaping is done after grinding 15.20 g of the solid and mixing itwith 3.80 g of alumina (Pural SB type) and 16 ml of distilled water inan extruding syringe (1.8 mm diameter).

After drying again overnight at 120° C., the extrudates are calcined at650° C. during 2 hours.

The quantity of recovered material is 14 g.

Finally, the deposit of platinum takes place by impregnating in static12.5 g of this solid with a solution prepared in the following way: to0.252 g of a chloroplatinic acid at 25% of Pt, distilled water is addedto give 6.9 ml of a solution. The impregnation at porous volume is thencarried out.

Finally, the solid is dried overnight at 120° C. and then calcined for 4hours at 480° C.

It should be noted that acetone is miscible with water in allproportions.

Catalyst G

This Example shows the preparation of an acid catalyst (Catalyst G) witha pure mass sulfated zirconia base, wherein the zirconia gel is washedwith methanol.

70 g of ZrO(NO₃)₂, 6H₂O is dissolved in 700 ml of warm water (80° C.)with agitation. After cooling at room temperature, the zirconiahydroxide gel is precipitated by adding 50 ml of an ammonia solution at28%, still with agitation. The final pH is 9.5.

The mixture is then filtered and washed with water over a Buchner funneluntil pH7. The gel is then washed with methanol: it is first rinsed inthe funnel with 50 ml of methanol and it is then transferred in a beakerin with it is dispersed in 600 ml of methanol with agitation at roomtemperature and then filtered again.

This washing step (dispersing and filtering) is repeated five times.

The gel is then dried overnight at 60° C., under vacuum in an oven.

The sulfation step is carried out by adding 198 ml of sulfuric acid 0.5M to 30.44 g of gel and by maintaining a static contact for 15 minutes.The gel is then filtered over a Buchner funnel, in which it is rinsedwith 90 ml of sulfuric acid 0.5 M, and it is then dried overnight at120° C., under atmospheric pressure, in a muffle oven.

The shaping is done with an extruding syringe (1.5 mm diameter), aftergrinding 30.44 g of the solid and malaxating it with 7.61 g of Pural SBtype alumina and 29 ml of distilled water.

After drying again overnight at 120° C. under atmospheric pressure, in amuffle oven, the extrudates are calcined at 650° C. for 3 hours.

Finally, the deposit of platinum takes place by impregnation at porousvolume, in order to obtain a final content of 0.5 wt % of platinumdeposited on the catalyst. To this end, 23.50 g of extrudates areimpregnated with 8.23 ml of an aqueous solution of chloroplatlnic acidat 5.32 wt % of Pt.

Finally, the solid is dried at 120° C. overnight, under atmosphericpressure in a muffle oven, and calcined at 480° C. for 4 hours.

Note: methanol is miscible with water in all proportions.

Catalyst H

This Example shows the preparation of an acid catalyst (Catalyst H) witha pure mass sulfated zirconia base, wherein the zirconia gel is washedwith ethanol.

35.5 g of ZrO(NO₃)₂, 6H₂O is dissolved in 350 ml of distilled water,with agitation.

The zirconium gel is precipitated by adding 25 ml of an ammonia solutionat 28%, still with agitation. The mixture is filtered over a Buchnerfunnel and washed with water until pH7. After spinning over the Buchnerfunnel, the gel is washed with acetone: it is transferred in a beaker,in which it is dispersed in 300 ml of ethanol. The mixture is agitatedduring 15 minutes, then the gel is filtered over a Buchner funnel. Afterwashing again twice with ethanol, in the same conditions, the gel isdried overnight at 60° C.

14.60 g of solid is obtained.

The sulfation reaction is carried out by adding 92 ml of sulfuric acid 1N to 14.20 g of the gel and maintaining a contact with agitation during15 minutes. After spinning over a Buchner funnel, the mixture is driedovernight at 120° C.

After drying again overnight at 120° C., the extrudates are calcined at650° C. for 2 hours.

11.82 g of material is recovered.

Finally, the deposit of platinum takes place by impregnating in staticthe 11.82 g of solid with a solution prepared as follows: to 0.236 g ofa solution of chloroplatinic acid at 25% of Pt, distilled water is addedto give 4.5 ml of solution. The impregnation at porous volume is thencarried out.

The solid is lastly dried at 120° C. overnight and is calcined at 480°C. for 4 hours.

Note: the solubility of ethanol in water is of more than 10 g/100 ml atatmospheric pressure and at 23° C.

Properties of the Pure Mass Catalysts Consistent with the Invention

Table V hereafter shows the properties of the catalyst samples obtainedaccording to the methods of preparation described above.

In these four samples, the sulfated zirconia shows a quadratic typecrystalline structure; This structure is determined by X-raydiffraction.

In the following Table, S, Vp and Rp respectively designate the surfacearea, the pore volume and the average pore diameter of the catalyst.These characteristics have been determined using the B.E.T. method(Brunauer, Emmett, Teller), by adsorption of nitrogen, as described inthe work by S. Lowell and J. E. Shields, “Powder Surface Area andPorosity”, Society of Petroleum Engineers, Advanced Technology Series(1984). The specific surface area S is deducted form the BET lineartransformation at five points (at the relative pressures P/Po=0.045;0.08; 0.15; 0.25 and 0.33), the pore volume Vp is determined accordingto the quantity of nitrogen adsorbed at P/Po=0.985 and the average porediameter Rp is calculated using the formula Rp=2 Vp/S.

Before determining these characteristics, the sample was subjected to apretreatment by primary vacuum dearation at 250° C. for at least 8hours.

TABLE V Al₂O₃ ZrO₂ (binder) S Vp Rp Catalyst (% by weight) (% by weight)(m²/g) (cm³/g) (10⁻¹⁰m) E 80 20 140 0.16 23 F 80 20   164.3 0.40 48 G 8020 157 0.34 43 H 80 20 150 0.28 35

The above results show that the preparation methods perfected byApplicants make it possible to create catalysts with a mass sulfatedzirconia base, in which zirconia has a crystalline structure and thathave textural properties (S, Vp, Rp) especially high, greater than knowncatalysts. In particular, catalysts F, G and H are new products becausethey have textural properties (S, Vp, Rp) remarkably high for that typeof catalyst containing crystalline sulfated zirconia, which have neverbeen obtained before in the prior art.

Tests of Activity of the Pure Mass Catalysts Consistent with theInvention

Test 1

The activity of samples E and F was determined in isomerization reactionof normal-hexane, in conventional conditions (T=145° C., P=30×10⁵ Pa,hydrogen/hydrocarbon (H₂/HC) ratio=3).

Table VI hereafter gives the results obtained. The activity of thesamples is represented by the percentage by weight of 2,2 dimethylbutane (2,2 DMB) in the isomerization effluent of the normal hexane.Various spatial speeds (or pph, feed weight per unit of catalyst weightand per hour) were used: pph=2 or 4 kg of feed kg⁻¹ of catalyst, h⁻¹.

At the beginning of each test, the catalyst is activated in situ with ahydrogen flow, the temperature of the reactor being first increasedprogressively from room temperature to 145° C. and then maintained at145° C. for two hours before beginning injecting the feed.

TABLE VI Activity (% 2,2 DMB) Catalyst Pph = 2 PpH = 4 E 30.7 26.4 F32.4 31.8

These tests show that Catalyst F according to the invention, and havingparticularly high textural properties, has a much higher activity thancatalyst E.

Test 2

The activity of catalysts F to H was determined in an isomerizationreaction of a complex feed, rather similar to industrial feeds, havingthe following composition (% by weight):

normal-pentane: 45%,

normal-hexane: 45%,

cyclo-hexane: 10%.

The test was conducted in a pilot reactor, in conventional conditionstypical of industrial conditions (T=145° C., P=30×10⁵ Pa,hydrogen/hydrocarbon (H₂/HC) molar ratio=3, pph=2 kg of feed. Kg⁻¹ ofcatalyst h⁻¹).

At the beginning of each test, the catalyst is activated in situ with ahydrogen flow, first increasing the temperature of the reactor from roomtemperature to 145° C. and then maintaining the temperature at 145° C.for 1 hour before injecting the feed.

The activity of the catalysts is represented by the TIN parameter(“Total Isomerization Number”), which is determined by the followingformula${{TIN} = {{\frac{{iso}\quad {C5}}{{NC5} + {{neo}\quad {C5}} + {{iso}\quad {C5}}} \cdot 100} + {\frac{2,2\quad {DMB}}{{2\quad {DMB}} + {2,3\quad {DMB}} + {2\quad {MP}} + {3\quad {MP}} + {n\quad {C6}}} \cdot 100}}},$

in which the contents by weight of the various are designated asfollows:

iso C5: iso-pentane,

nC5: normal-pentane,

neo C5: neo-pentane,

2,2 DMB: 2,2 dimethyl-butane,

2,3 DMB: 2,3 dimethyl-butane,

2MP: 2 methyl-pentane,

3 MP: 3 methyl-pentane,

nC6: normal-hexane.

The TIN corresponds to the content of highly branched paraffins in theeffluents of the isomerization test and it is a representation of theisomerizing activity of the tested catalyst.

Table VII hereafter shows the results obtained.

TABLE VII Catalyst TIN F 85.5  G 98.45 H 6.1

This Table demonstrates the excellent activity of the catalyst F, G, Hof the invention in industrial type conditions. This excellent activityis due to both the particularly high porosity and the crystallinestructure of zirconia in these pure mass catalysts.

This is to be compared with the results obtained with conventionalchlorinated alumina based catalysts, presently used in industrialisomerization reactors, which in the same conditions have a TIN of about90. Consequently the catalysts of the invention, based on pure masssulfated zirconia, have an activity level similar to that ofconventional superacid catalysts, having a chlorinated alumina basis.

Other properties of the catalysts of the invention (increased stability,easy handling, regenerability), compared to those of conventionalcatalysts comprising chlorinated alumina, make them speciallyadvantageous for a use in reactions with an acid or even superacidcatalyst.

What is claimed is:
 1. A solid acid catalyst, comprising pure masssulfated zirconia and at least one hydrogenating transition metal,wherein the zirconia is in crystalline state and wherein the catalysthas a surface area greater than or equal to 150 m²/g, a pore volumegreater than or equal to 0.2 cm³/g and an average pore diameter greaterthan or equal to 20×10⁻¹⁰ m.
 2. The solid acid catalyst as set forth inclaim 1, wherein the surface area is greater than or equal to 150 m²/g,the pore volume is greater than or equal to 0.25 cm³/g and the averagepore diameter is greater than or equal to 30×10⁻¹⁰ m.
 3. The solid acidcatalyst as set forth in claim 1, wherein the crystallized sulfatedzirconia has a quadratic or monoclinic crystalline structure.
 4. Thesolid acid catalyst as set forth in claim 1, wherein the catalyst has anapparent filling density between 0.5 and
 3. 5. The solid acid catalystas set forth in claim 1, wherein the zirconia is partially sulfated andthe sulfated zirconia has a sulfur content in the form of sulfatebetween 1% and 10% by weight based on the weight of the zirconia.
 6. Thesolid acid catalyst as set forth in claim 1, containing from 50 to 95percent by weight of sulfated zirconia.
 7. The solid acid catalyst asset forth in claim 1, wherein the hydrogenating transition metal is anelement of Group VIII of the Periodic table of elements.
 8. The solidacid catalyst as set forth in claim 1, wherein the average pore diameteris greater than or equal to 30×10⁻¹⁰ m.
 9. The solid acid catalystaccording to claim 1, wherein the zirconia is totally sulfated.
 10. Thesolid catalyst according to claim 6, containing from 70 to 90 percent byweight of sulfated zirconia.
 11. The solid acid catalyst according toclaim 1, wherein the hydrogenating transition metal is platinum.
 12. Thesolid catalyst according to claim 1, further comprising from 5 to 50% byweight of a binder material.
 13. The solid catalyst according to claim12, further comprising from 10 to 30% by weight of a binder material.14. The solid catalyst according to claim 12, wherein the bindermaterial is selected from the group consisting of aluminas, silicas,silica-aluminas, alumino-silicates, clays and combinations thereof. 15.The solid acid catalyst according to claim 3, wherein the crystallizedsulfated zirconia has a quadratic crystalline structure.
 16. The solidacid catalyst according to claim 5, wherein the zirconia is partiallysulfated and the sulfur content in the form of sulfate is between 1% and5% based upon the weight of the zirconia.
 17. A method of making a solidacid catalyst containing crystallized pure mass sulfated zirconia,comprising the steps of: a) adding a basic solution to a zirconium saltsolution to produce a mixture containing a precipitate of hydratedzirconia, b) filtering the mixture and washing the precipitate withwater to form a solid, c) washing the solid with a water soluble polarorganic solvent, at least one time, d) drying the solid, e) sulfatingthe solid, f) shaping the solid and first calcining at a temperature ofat least 550° C., g) depositing the hydrogenating transition metal, andh) final calcining.
 18. The method as set forth in claim 17, wherein thezirconium salt is chosen from the group consisting of zirconium andzirconyles nitrates, chlorides, acetates, formates, oxalates, zirconiumpropylates and butylates.
 19. The method as set forth in claim 17,wherein step e) comprises impregnating the solid with a sulfating agent,drying, and calcining the solid wherein the sulfating agent is eitherpure sulfuric acid or a solution of sulfuric acid, an ammonia sulfateaqueous solution, or another precursor of sulfate ions.
 20. The methodas set forth in claim 17, wherein step g) comprises impregnating thesolid with a solution of a compound of the hydrogenating transitionmetal, followed by a drying step.
 21. The method as set forth in claim20, wherein the hydrogenating transition metal is platinum, and theimpregnating step is conducted with a solution of a platinum compoundselected from the group consisting of chloroplatinic acid and complexcompounds of platinum.
 22. The method according to claim 17, comprisingthe further step of introducing a binder material immediately beforestep f).
 23. The method according to claim 22 wherein the bindermaterial is in the amount of 5 to 50% by weight.
 24. The methodaccording to claim 22 wherein the binder material is in the amount of 10to 30% by weight.
 25. The method according to claim 22 wherein thebinder material is selected from the group consisting of aluminas,silicas, silica-aluminas, alumino-silicates, clays and combinationsthereof.
 26. The method according to claim 17, wherein step c) compriseswashing the solid with a water soluble polar organic solvent at leastthree times.
 27. The method according to claim 17, wherein step c)comprises washing the solid with a water soluble polar organic solventhaving a solubility in water of at least 5 g/100 ml at 23° C., underatmospheric pressure.
 28. The method according to claim 17, wherein stepc) comprises washing the solid with a water soluble polar organicsolvent, wherein the solvent and water are miscible in all proportions.29. The method according to claim 17, wherein step c) comprises washingthe solid with a water soluble polar organic solvent having a boilingpoint less than 100° C.
 30. The method according to claim 25 wherein thebinder material is alumina.
 31. A solid acid catalyst containingcrystallized pure mass sulfated zirconia prepared by a method comprisingthe steps of: a) adding a basic solution to a zirconium salt solution toproduce a mixture containing a precipitate of hydrated zirconia, b)filtering the mixture and washing the precipitate with water to form asolid, c) washing the solid with a water soluble polar organic solvent,at least one time, d) drying the solid, e) sulfating the solid, f)shaping the solid and first calcining at a temperature of at least 550°C., g) depositing the hydrogenating transition metal, and h) finalcalcining.
 32. The solid acid catalyst as set forth in claim 31, whereinthe zirconium salt is chosen from the group consisting of zirconium andzirconyles nitrates, chlorides, acetates formates, oxalates, zirconiumpropylates and butylates.
 33. The solid acid catalyst as set forth inclaim 31, wherein step e) comprises impregnating the solid with asulfating agent, drying, and calcining the solid wherein the sulfatingagent is either pure sulfuric acid or a solution of sulfuric acid, anammonia sulfate aqueous solution, or another precursor of sulfate ions.34. The solid acid catalyst as set forth in claim 31, wherein step g)comprises impregnating the solid with a solution of a compound of thehydrogenating transition metal, followed by a drying step.
 35. The solidacid catalyst as set forth in claim 34, wherein the hydrogenatingtransition metal is platinum, and the impregnating step is conductedwith a solution of a platinum compound selected from the groupconsisting of chloroplatinic acid and complex compounds of platinum. 36.The solid acid catalyst according to claim 31, comprising the furtherstep of introducing a binder material immediately before step f). 37.The solid acid catalyst according to claim 36 wherein the bindermaterial is in the amount of 5 to 50% by weight.
 38. The solid acidcatalyst according to claim 36 wherein the binder material is in theamount of 10 to 30% by weight.
 39. The solid acid catalyst according toclaim 36 wherein the binder material is selected from the groupconsisting of aluminas, silicas, silica-aluminas, alumino-silicates,clays and combinations thereof.
 40. The solid acid catalyst according toclaim 31, wherein step c) comprises washing the solid with a watersoluble polar organic solvent at least three times.
 41. The solid acidcatalyst according to claim 31, wherein step c) comprises washing thesolid with a water soluble polar organic solvent having a solubility inwater of at least 5 g/100 ml at 23° C., under atmospheric pressure. 42.The solid acid catalyst according to claim 31, wherein step c) compriseswashing the solid with a water soluble polar organic solvent, whereinthe solvent and water are miscible in all proportions.
 43. The solidacid catalyst according to claim 31, wherein step c) comprises washingthe solid with a water soluble polar organic solvent having a boilingpoint less than 100° C.
 44. The solid acid catalyst according to claim39 wherein the binder material is alumina.